1. conclusion Room- temperature ferrimagnet with large magnetism P. S. Wang, H. J. Xiang* Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Fudan University, Shanghai 200433, P. R. China W. Ren Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444, P. R. China L. Bellaiche Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA Predicting a Ferrimagnetic Phase of Zn 2 FeOsO 6 with Strong Magnetoelectric Coupling Multiferroic materials, in which ferroelectric and magnetic ordering coexist, are of practical interest for the development of novel memory devices that allow for electrical writing and non-destructive magnetic readout operation. The great challenge is to create room temperature multiferroic materials with strongly coupled ferroelectric and ferromagnetic (or ferrimagnetic) orderings. BiFeO 3 is the most heavily investigated single-phase multiferroic to date due to the coexistence of its magnetic order and ferroelectric order at room temperature. However, there is no net magnetic moment in the cycloidal (antiferromagnetic-like) magnetic state of bulk BiFeO 3, which severely limits its realistic applications in electric field controlled memory devices. Here, we predict that LiNbO 3 -type Zn 2 FeOsO 6 is a new multiferroic with properties superior to BiFeO 3. First, there are strong ferroelectricity and strong ferrimagnetism at room temperature in Zn 2 FeOsO 6. Second, the easy-plane of the spontaneous magnetization can be switched by an external electric field, evidencing the strong magnetoelectric coupling existing in this system. Our results suggest that ferrimagnetic 3d-5d LiNbO 3 -type material may therefore be used to achieve voltage control of magnetism in future memory devices. Abstract novel memory devices : electrical writing and magnetic readout Design room-temperature multiferroics with strong magnetoelectric coupling Large magnetic moment and ferroelectric polarization Motivations systemsmagnetismT(K)Polarization BiFeO 3 AFM643100 Zn 2 FeTaO 6 AFM2250 Ca 2 FeOsO 6 FIM3200 Some typical multiferroics Zn 2 FeTaO 6 Ca 2 FeOsO 6 Zn 2 FeOsO 6 High Tc; large M R3 space group 54.7 uC/cm^2 GA search Tolerance factor: Zn 2+ displacement Space groupR3P2 1 /nC2 Energy(eV/f.u.)00.090.220.45 R3 structure of Zn 2 FeOsO 6 FiM structure of Zn 2 FeOsO 6 2 Magnetic anisotropy in R3 Zn 2 FeOsO 6 Exchange pathJ 1 (Fe-Os)J 2 (Fe-Os)J 3 (Os-Os)J 4 (Os-Os) Effective J (meV)31.6829.627.253.24 Ferrimagnetic structure with Fe and Os spins in the ab plane Easy plane: Single-ion anisotropy, A Fe =0.89meV; A Os =-0.34meV Spin canting: DM interaction, Total energy curve is well described by the effective Hamiltonian Thermodynamic properties of the magnetism Tc=394K !!! In-plane total spin moment: > 2 Space groupR3P2 1 /n Tc(K)394344356 Magnetoelectric coupling in Zn 2 FeOsO 6 Double well potential with an energy barrier of 0.09eV/f.u. Reference structure is 8 symmetrically equivalent directions 71 。 or 109 。 switch of the FE domains by electric field Strong ME coupling due to strong magnetic anisotropy ! 1.Strong FE and strong FiM at room temperature in Zn 2 FeOsO 6 2.The easy plane of the spontaneous magnetization can be switched by an external electric field For more information, see Phys. Rev. Lett. 114, 147204 (2015)